The present invention relates to a magnetic sheet, a method of manufacturing a magnetic sheet, and a wireless communications device.
Along with reductions in weight and size of portable electronic devices, the electronic devices are increasingly being configured for non-contact type charging. The non-contact type charging relies on a wireless power charging scheme for operation. The wireless power charging scheme uses magnetic coupling (or inductive coupling) for charging of a battery of the electronic device without requiring the connection of physical electrical contact(s).
The wireless power charging scheme is a scheme in which charging is performed through the use of electromagnetic induction. In general, a primary coil (a transmitting coil) is provided in a charger (a wireless power transmitting device), a secondary coil (a receiving coil) is provided in a charging target (a wireless power receiving device), and a current is generated in the secondary coil according to inductive coupling between the primary coil and the secondary coil to provide energy used to charge a battery of the charging target.
In accordance with this disclosure, a magnetic sheet performing a shielding function is disposed between the receiving coil and the battery. The shielding sheet serves to shield the battery from a magnetic field generated by the receiving coil and allow electromagnetic waves generated by the wireless power transmitting device to be effectively transmitted to the wireless power receiving device.
Such a magnetic sheet is processed as a film and applied as is, or, in regard to reducing eddy current loss, a technique of fracturing a magnetic sheet and additionally processing the fractured magnetic sheet into a plurality of fragments to be used has been proposed. In the process of fracturing a magnetic sheet, a method of pressing one surface of the magnetic sheet has generally been used, and accordingly, fragments P having random shapes and arrangements are formed in the magnetic sheet 30 as illustrated in FIG. 1.